Amethyst was made on Earth, setting her apart from Garnet and Pearl, as she never knew what it was like to be forced into the role she was made for. She's reckless, loud and often vulgar, with an inability to take most things seriously. However, her heart is in the right place, and as the series progresses she grows into her role as a Crystal Gem and Steven's caretaker without losing her fun-loving side. Secretly, Amethyst struggles with her self-worth, believing herself to be worse than all the other Crystal Gems. This isn't aided by the discovery that she's defective--she emerged from the Kindergarten too late, and as a result she's only half the size she should be as a Quartz gem. She unhealthily bottles up these feelings, in an attempt to hide her low self-esteem from the others under a carefree mask. Amethyst is arguably the closest gem to Steven, and the two of them help each other overcome their insecurities about being "wrong".

Voice reference: https://www.youtube.com/watch?v=duh_oCVSAZ0 (Amethyst's voice is a tricky one to imitate - so I'd suggest focusing more on the emotion and emphasis behind the words than the voice itself)